Intel.RTM. has provided a specification, ATX, for the personal computer industry. The ATX motherboard provides several functions such as soft-off, timer-on, and multi-wake-up functions such as waked up by the modem, LAN, mouse, and keyboard . . . etc. The ATX motherboard is also compatible with the PC98 specification and the advance configuration and power interface (ACPI). Conventionally, a computer system may have two global system states: a mechanical off state and a working state. However, a computer with an ATX motherboard may be in a mechanical off state, a soft-off state, a sleeping state or a working state. This may meet problems in a power-loss situation. At the beginning, an Intel chipset can only provides a working state for the ATX computer when the power is supplied again. However, in many situations, a working state is not expected. To solve the problem, Intel provides a circuit for the user to determine whether the system is in a working state or a soft-off state when the power is provided again.
However, there still exists some problems. When the power is lost, some parameters needed for the system operation may be lost. These parameters are provided by BIOS and may be adjusted by the user. Unless the system is reset, these parameters cannot be recovered. If a soft-off state is chosen by an Intel chipset user, these parameters cannot be recovered unless the user presses the bottom to reset the system.
An ATX power supply can be in a waiting state to wait for a wake-up event. A waiting voltage 5VSB is provided by the ATX power supply to the system to enable the wake-up ability. A signal SUSC is outputted by the chipset. When the signal SUSC is inactive, the chipset identifies that the system is in a working state. Oppositely, if the signal SUSC is active, it represents that the chipset identifies that the system is in a waiting state which is capable of executing an wake-up event. However, the conventional chipset cannot properly generate a correct SUSC signal after a power loss. For example, an Intel PIIX4 south-bridge chipset can only generate an inactive SUSC signal when the waiting voltage 5VSB is lost and provided again, no matter whether the system is in a working state or a waiting state. Consequently, the data needed for the wake-up event is lost and cannot be reset since the chipset identifies that the system is in a working state even if it is actually in a waiting state. Unless the user presses the panel button to restart the computer, the wake-up functions will be invalid.
Such a process is relatively inconvenient for the user. For example, a timer-on function is set that the computer is turned on at 6:00 a.m. and a power-loss happens at midnight. Although the power may be supplied again before 6:00 a.m., the timer-on function still cannot be executed since the parameter about when to turn on the computer is lost. Other functions about the wake-up event cannot be executed because of the same reason.
It is then attempted by the present invention to solve the above-mentioned problems.